Electrosurgical unit and system

ABSTRACT

Systems, such as an electrosurgical unit, and method for use with an active electrode and a plurality of return electrodes are disclosure. An electrosurgical treatment is provided to tissue via the active electrode at a treatment site and a first return electrode of the plurality of return electrodes at the treatment site. An impedance measurement is received or determined of an impedance in the tissue between the active electrode at the treatment site and a second return electrode of the plurality of return electrodes at a site remote from the treatment site.

CROSS REFERENCE TO RELATED APPLICATION

This Non-Provisional Utility Application claims benefit to U.S.Provisional Application No. 62/445,034, filed Jan. 11, 2017, titled“ELECTROSURGICAL UNIT AND SYSTEM,” the entirety of which incorporatedherein by reference.

BACKGROUND

This disclosure relates generally to the field of medical devices,systems and methods for use in surgical procedures. More specifically,this disclosure relates to electrosurgical devices, units, systems andmethods that can provide for cutting, coagulation, hemostasis, orsealing of bodily tissues including bone with an electrosurgical device.

Electrosurgery includes such techniques as cutting, coagulation,hemostasis, and/or sealing of tissues with the aid of electrodesenergized with a suitable power source. Typical electrosurgical devicesapply an electrical potential difference or signal between an activeelectrode and a return electrode on a patient's grounded body in amonopolar arrangement or between an active electrode and a returnelectrode on the device in bipolar arrangement to deliver electricalenergy to the area where tissue is to be affected. The electrosurgicaldevices are typically held by the surgeon and connected to the powersource, such as an electrosurgical unit having a power generator, viacabling.

Electrosurgical devices pass electrical energy through tissue betweenthe electrodes to provide coagulation to control bleeding and hemostasisto seal tissue. Electrosurgical devices can also cut tissue through theuse of plasma formed on the electrode. Tissue that contacts the plasmaexperiences a rapid vaporization of cellular fluid to produce a cuttingeffect. Typically, cutting and coagulation are often performed withelectrodes in the monopolar arrangement while hemostasis is performedwith electrodes in the bipolar arrangement. Historically, two distinctelectrosurgical devices, one monopolar and the other bipolar, were usedto perform different functions in surgery, such as tissue cutting andcoagulating and tissue sealing. Some electrosurgical devices capable ofperforming multiple techniques such as cutting and coagulating tissue orcutting, coagulating, and sealing tissue, including fluid-assistedsealing of tissue, have been developed.

Dry-tip electrosurgical devices can adversely affect tissue and surgicalprocedures by desiccating or perforating tissue, causing tissue to stickto the electrodes, burning or charring tissue, and generating smoke atthe surgical site. More recently, fluid-assisted electrosurgical deviceshave been developed that use saline to inhibit such undesirable effectsas well as to control the temperature of the tissue being treated and toelectrically couple the device to the tissue. Fluid-assistedelectrosurgical devices have been developed which, when used inconjunction with an electrically conductive fluid such as saline, may bemoved along a tissue surface without cutting the tissue to seal tissueto inhibit blood and other fluid loss during surgery.

Fluid-assisted electrosurgical devices apply radiofrequency (RF)electrical energy and electrically conductive fluid to provide forsealing of soft tissues and bone in applications of orthopedics (such astotal hip arthroplasty, or THA, and total knee arthroplasty, or TKA),spinal oncology, neurosurgery, thoracic surgery, and cardiac implantableelectronic devices as well as others such as general surgery within thehuman body. The combination of RF energy and the electrically conductivefluid permits the electrosurgical device to operate at approximately 100degrees Celsius, which is nearly 200 degrees Celsius less thantraditional electrosurgical devices. Typically, hemostasis is performedwith fluid-assisted devices having electrodes in the bipolar arrangementthat are referred to as bipolar sealers. By controlling bleeding,bipolar sealers have been demonstrated to reduce the incidence ofhematoma and transfusions, help maintain hemoglobin levels, and reducesurgical time in a number of procedures, and may reduce the use ofhemostatic agents.

Electrical signals can be applied to the electrodes either as a train ofhigh frequency pulses or as a continuous signal typically in theradiofrequency (RF) range to perform the different techniques. Thesignals can include a variable set of parameters, such as power orvoltage level, waveform parameters such as frequency, pulse duration,duty cycle, and other signal parameters that may be particularly apt orpreferred for a given technique. For example, a surgeon could cut tissueusing a first RF signal having a set of parameters to form plasma andcontrol bleeding using a second RF signal having another set ofparameters more preferred for coagulation. The surgeon could also useelectrodes in a bipolar arrangement or a bipolar electrosurgical devicefor hemostatic sealing of the tissue that would employ additional RFsignals having another set of parameters.

Electrosurgical units that deliver power to the electrosurgical devicesalso control the power to provide an effective treatment. For example,electrosurgical units can measure the difference in voltages between theactive electrode and the return electrode and divide this difference bythe measured current between the electrodes to calculate the electricalimpedance of the tissue. The amount of tissue impedance can be relatedto the amount of energy delivered to a treatment site. Impedance oftissue will increase with thermal delivery until the impedance reaches aplateau, at which point additional thermal delivery will no longereffectively treat the tissue as intended. As electrical resistance oftissue located between two electrodes increases, the electrosurgicalcurrent will seek a new path from the active electrode to the returnthrough tissue with a lower resistance, thereby spreading the deliveryof thermal energy. Electrosurgical units can measure tissue impedanceand selectively adjust the power output, such as reduce power or ceasepower, to the electrosurgical device to avoid excessive or unintendedtreatment or thermal delivery to the tissue.

In some circumstances of bipolar treatment, however, tissue impedance isdifficult to detect. For example, the presence of a conductive fluidsuch as saline in the area of thermal delivery during hemostasis may adda parallel electrical load to the tissue between the active electrodeand the return electrode. The conductive fluid may provide a lessresistive path for electrical energy between the electrodes than tissue.Further, the conductive fluid, unlike tissue, generally provides aconstant impedance when subjected to electrical energy. The parallelload in the presence of tissue can affect the impedance measurement inthe form of electrical noise that can adversely affect the ability ofthe electrosurgical unit to determine when or whether to adjust power.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription.

Impedance of tissue at the treatment site will increase with thermaldelivery from an electrosurgical device until the impedance reaches aplateau, at which point thermal delivery will no longer effectivelytreat the tissue. At this point, an electrosurgical unit can adjustpower, such as cut power or reduce power, in the signal to the activeelectrode, for example to cease treatment. In some circumstances ofbipolar treatment, however, the impedance and the impedance plateau aredifficult to detect with a bipolar electrosurgical device and typicalelectrosurgical units. For example, the presence of a conductive fluidsuch as saline in the area of thermal delivery during hemostasis may adda parallel electrical load to the tissue between the active electrodeand the return electrode of the bipolar electrosurgical device.

The present disclosure relates to a method and system that may improvethe ability to detect thermal effect via tissue impedance particularlyin the bipolar treatment of tissue with the presence of fluid. Anelectrosurgical device in a bipolar configuration, which can disperse afluid, is coupled to an electrosurgical unit. The electrosurgical deviceincludes an active electrode and first return electrode that isconfigured to provide electrosurgical treatment of tissue at the tissuetreatment site. A second return electrode, such as a pad dispersiveelectrode used in monopolar treatment of tissue or other returnelectrode, is also coupled to the electrosurgical unit to and to thetissue at a site remote from the treatment site. In one example, thefirst return electrode can be operably coupled to the second returnelectrode provide the voltage of the first return electrode. The voltagedifference between the active electrode and the second return electrodeas well as a current from the second return electrode are measured todetermine tissue impedance. The impedance of the tissue between theactive electrode and the first return electrode at the tissue treatmentsite may or may not be measured. Changes in the tissue impedance betweenthe active electrode and the second return electrode can be used todetect thermal effect, such as an impedance plateau without theassociated noise or issues introduced with the conductive fluid at thetreatment site.

In one aspect, the present disclosure relates to method for use with anactive electrode and a plurality of return electrodes. For example, thepresent disclosure relates to a method for use with electrosurgicaldevice having an active electrode and a first return electrode toprovide a bipolar treatment to tissue at a treatment site and to remoteelectrode disposed on the tissue at a remote site remote from thetreatment site. An electrosurgical treatment is provided to tissue viathe active electrode at a treatment site and a first return electrode ofthe plurality of return electrodes at the treatment site. An impedancemeasurement is received or determined of an impedance in the tissuebetween the active electrode at the treatment site and a second returnelectrode of the plurality of return electrodes at a site remote fromthe treatment site. The treatment can be adjusted based on the impedancemeasurement. In one example, the method is implemented as anon-transitory computer readable medium to store computer executableinstructions to control a processor. For instance, the method isimplemented with an electrosurgical unit such as an electrosurgicalgenerator.

In one example, a first impedance measurement is received of animpedance in the tissue between the active electrode at the treatmentsite and the first return electrode at the treatment site. A secondimpedance measurement is received of an impedance in the tissue betweenthe active electrode at the treatment site and a second return electrodeof the plurality of return electrodes at a site remote from thetreatment site. The treatment can be adjusted based on a comparison ofthe first impedance measurement with the second impedance measurement

An electrosurgical unit can include a radio-frequency (RF) circuit, adetection circuit, a processor or controller, and various connections toelectrodes configured to provide treatment and take measurements ofelectrical signals in tissue at a treatment site and at a remote site.For example, the RF circuit is operably coupled to an output having anactive electrode connection and a first return connection in which theRF circuit configured to provide a bipolar operation to via the activeelectrode connection. The detection circuit configured to be operablycoupled to the active electrode connection and the first returnelectrode connection, the detection circuit further configure to beoperably coupled to a second return electrode connection. The processoroperably coupled to the detection circuit and configured to detect apotential difference between the active electrode connection and thesecond return electrode connection and a current in the second returnelectrode connection, and to determine an impedance measurement based onthe potential difference and the current during bipolar operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view illustrating an embodiment of an electrosurgicalsystem according to the present disclosure including an exampleelectrosurgical unit in combination with a fluid source and examplehandheld electrosurgical device.

FIG. 2 is a front view illustrating the example electrosurgical unit ofFIG. 1.

FIG. 3 is a perspective view illustrating an example of theelectrosurgical device of FIG. 1 including a bipolar electrode assembly.

FIG. 4 is a schematic view of an environment including theelectrosurgical system of FIG. 1 treating tissue.

FIG. 5 is a schematic view illustrating example features of theelectrosurgical unit in the system of FIG. 1.

FIG. 6 is a block diagram illustrating an example method that can beused with the electrosurgical system of FIG. 1 in the exampleenvironment of FIG. 4 such as with the example electrosurgical unit ofFIG. 5.

FIG. 7 is a block diagram illustrating another example method that canbe used with the electrosurgical system of FIG. 1 in the exampleenvironment of FIG. 4 such as with the example electrosurgical unit ofFIG. 5.

DETAILED DESCRIPTION

Throughout the description, like reference numerals and letters indicatecorresponding structure throughout the several views. Also, anyparticular features(s) of a particular exemplary embodiment may beequally applied to any other exemplary embodiment(s) of thisspecification as suitable. That is, features between the variousexemplary embodiments described herein are interchangeable as suitableand may not be exclusive. From the specification, it should be clearthat the terms “distal” and “proximal” are made in reference to a userof the device.

FIG. 1 illustrates a front view of one example of a system 40 thatincludes an electrosurgical unit 10 in combination with an examplehandheld electrosurgical device 30. The device 30, in one example, canbe configurable for use in a bipolar mode. An additional monopolardevice, not shown, may also be used in combination with theelectrosurgical unit 10 as part of system 40. In another example, thedevice 30 is a multipurpose device configurable for use in cutting andsealing including electrocautery and coagulation in a monopolar modeusing a monopolar electrode and configurable to provide hemostaticsealing of tissue including bone with a fluid in a bipolar mode using atleast a second monopolar electrode in combination with a fluid source20, or for other electrical surgical procedures.

The system 40 can be carried on a movable cart 2 having a support member4 comprising a hollow cylindrical post which includes a platform 6comprising a pedestal table to provide a flat, stable surface forlocation of the electrosurgical unit 10. Cart 2 can include a pole 8having a height that can be adjusted by sliding the pole 8 up and downand secured in position with a set screw. The pole can include a crosssupport with loops at the end to form a hook. Fluid source 20 can besupported at the top of pole 8 via the hook. The movable cart 2 and itsfeatures are provided for illustration as an example.

Fluid source 20 may comprise a bag of fluid from which fluid 12 may flowthrough a drip chamber 14, to delivery tubing 16 and to handheldelectrosurgical device 30. In one example, the fluid 12 includes salineand can include physiologic saline such as sodium chloride (NaCl) 0.9%weight/volume solution. Saline is an electrically conductive fluid, andother suitable electrically conductive fluids can be used. In otherexamples, the fluid may include a nonconductive fluid, such as deionizedwater, which may still provide advantages over using no fluid and maysupport cooling of portions of electrosurgical device 30 and tissue orreducing the occurrence of tissue sticking to the electrosurgical device30.

The fluid delivery tubing 16 in the example passes through pump 22 toconvey fluid to the electrosurgical device 30 and control fluid flow.Pump 22 in one example is a peristaltic pump such as a rotaryperistaltic pump or a linear peristaltic pump. A peristaltic pump canconvey the fluid through the delivery tubing 16 by way of intermittentforces placed on the external surface of the delivery tubing.Peristaltic pumps are often applied during use of the electrosurgicaldevice 30 because the mechanical elements of the pump places forces onthe external surface of the delivery tubing and do not come into directcontact with the fluid, which can reduce the likelihood of fluidcontamination. Other examples of system 40 might not include a pump, andfluid can be is provided to the electrosurgical device 30 via gravity.

The example electrosurgical unit 10 is configured to provide bipolar orboth monopolar and bipolar radio-frequency (RF) power output to aspecified electrosurgical instrument such as electrosurgical device 30.In one example, the electrosurgical unit 10 can be used for delivery ofRF energy to instruments indicated for cutting and coagulation of softtissue and for delivery of RF energy concurrent with fluid toinstruments indicated for hemostatic sealing and coagulation of softtissue and bone. In one example, the electrosurgical unit 10 is capableof simultaneously powering specified monopolar and bipolarelectrosurgical instruments but may include a lock out featurepreventing both monopolar and bipolar output from being simultaneouslyactivated.

During monopolar operation of an electrosurgical device (not shown), afirst electrode, often referred to as the active electrode, is providedwith electrosurgical device to be used at a surgical site while a returnelectrode, which can be referred to as the indifferent or neutralelectrode, is provided remote from the surgical site and often in theform of a ground pad dispersive electrode 32 located on a patient. Forexample, the pad dispersive electrode 32 is typically on the back,buttocks, upper leg, or other suitable anatomical location duringsurgery. In such a configuration, the pad dispersive electrode 32 isoften referred to as a patient return electrode. An electrical circuitof RF energy is formed between the active electrode and the paddispersive electrode 32 through the patient.

During bipolar operation of electrosurgical device 30 as illustrated, anactive electrode providing the first electrical pole and anotherelectrode, often referred to as the return electrode providing a secondelectrical pole, is provided at the surgical site, such as part of thedevice 30. An electrical circuit of RF energy is created between thefirst and second poles of the device 30. Historically, the paddispersive electrode 32 was not used in bipolar operation. In thepresent example of bipolar operation of electrosurgical device 30,however, a second return electrode, which applied to the patient in aregion typically remote from the surgical site, such as the dispersiveelectrode 32, is used in during bipolar operation of electrosurgicaldevice 30. Both the second return electrode, such as the dispersiveelectrode 32, and the return electrode on the surgical device 30, i.e.,a first return electrode, are coupled together and to a measurementcircuit in the electrosurgical unit 10. A significant portion of thecurrent may not flow through the patient's body to the second returnelectrode, such as the pad dispersive electrode 32 as in a the monopolarmode, but rather through a localized portion of tissue between the polesof the device 30, i.e., the active and first return electrodes.

The electrosurgical device 30 in the example is connected toelectrosurgical unit 10 via cable 24. Cable 24 includes plugs 34 thatconnect with receptacles 36 on the electrosurgical unit 10. In oneexample, a receptacle can correspond with an active electrode receptacleand one or more receptacles can correspond with controls on theelectrosurgical device 30. Still further, a receptacle can correspondwith a second active electrode receptacle. An additional cable mayconnect the pad dispersive electrode 32 to a pad receptacle of theelectrosurgical unit 10. In some examples, delivery tubing 16 and cable24 are combined to form a single cable 26.

In one example, the electrosurgical unit 10 is capable of operating inat least bipolar mode with a connection for a second return electrode,such as for the pad dispersive electrode. In another example, theelectrosurgical unit 10 is cable of operating in both a bipolar mode anda monopolar mode. In still another example, the electrosurgical unit 10is capable of operating in monopolar and bipolar modes as well asmultiple functions with a mode such as a monopolar cutting function, amonopolar coagulation function, and monopolar hemostasis or tissuesealing function as well as at least a bipolar hemostasis or tissuesealing function. For example, monopolar RF energy is provided to thedevice 30 at a first power level and/or a first waveform (collectivelyfirst, or cutting RF energy setting) for the monopolar cutting function.Cutting RF energy for a cut function may be provided at a relatively lowvoltage and a continuous current (100% on, or 100% duty cycle). Nominalimpedance can range between 300 to 1000 ohms for the cutting function.At a power setting of 90 Watts for cutting, voltage can range fromapproximately 164 to 300 volts root mean square (RMS). In the monopolarcoagulation function, monopolar RF is energy is provided to theelectrode at a second power level and/or second waveform (collectivelysecond, or coagulating RF energy setting) that is different than atleast one of the first power level or the first waveform. For example,coagulating RF energy for a coagulation function may be provided at arelatively higher voltage than the cut voltage and with a pulsedcurrent, such as 1% to 6% on and 99% to 94% off, respectively (or 1% to6% duty cycle). Other duty cycles are contemplated.

The electrosurgical unit 10 may provide bipolar RF energy at a thirdpower level and/or third waveform (collectively third, or hemostaticsealing RF energy setting) along with fluid for a (generally lowvoltage) hemostasis or tissue sealing function that may be the same asor different than the cutting and coagulating RF settings provided tothe device 30 for the cut function or the coagulation function. In oneexample, hemostatic sealing energy can be provided with a continuouscurrent (100% duty cycle). Nominal impedance can range between 100 to400 ohms for the hemostatic sealing function. At a power setting of 90Watts for hemostatic sealing, voltage can range from approximately 95 to200 volts RMS.

In one example, the electrosurgical unit 10 provides RF energy to theactive electrode as a signal having a frequency in the range of 100 KHzto 10 MHz. Typically this energy is applied in the form of bursts ofpulses. Each burst typically has a duration in the range of 10microseconds to 1 millisecond. The individual pulses in each bursttypically each have a duration of 0.1 to 10 microseconds with aninterval between pulses of 0.1 to 10 microseconds. The actual pulses areoften sinusoidal or square waves and bi-phasic, that is alternatingpositive and negative amplitudes.

The electrosurgical unit 10 includes a power switch to turn the unit onand off and an RF power setting display to display the RF power suppliedto the electrosurgical device 30. The power setting display can displaythe RF power setting numerically in a selected unit such as watts.

The example electrosurgical unit 10 includes an RF power selectorcomprising RF power setting switches that are used to select or adjustthe RF power setting. A user can push one power setting switch toincrease the RF power setting and push the other power setting switch todecrease the RF power setting. In one example, power setting switchesare membrane switches, soft keys, or as part of a touchscreen. Inanother example, the electrosurgical unit may include more than onepower selectors such as a power selector corresponding with each of thedifferent monopolar settings used in the different functions.

The example electrosurgical unit 10 can also include fluid flow ratesetting display and flow rate setting selector. The display can includeindicator lights, and the flow rate selector can include switches.Pushing one of the flow rate switches selects a fluid flow rate, whichis than indicated in display.

Electrosurgical unit 10 can be configured to include control of the pump22. In this example, the speed of the pump 22, and the fluid throughput,can be predetermined based on input variables such as the RF powersetting and the fluid flow rate setting. In one example, the pump 22 canbe integrated with the electrosurgical unit 10.

FIG. 2 illustrates an example front panel of electrosurgical unit 10. Apower switch 58 can be used to turn the electrosurgical unit 10 on andoff. After turning the electrosurgical unit 10 on, an RF power settingdisplay 60 may be used to display the RF power setting numerically inwatts. The power setting display 60 may further comprise a liquidcrystal display (LCD).

Electrosurgical unit 10 may further comprise an RF power selector 62comprising RF power setting switches 62 a, 62 b that may be used toselect the RF power setting. Pushing the switch 62 a may increase the RFpower setting, while pushing the switch 62 b may decrease the RF powersetting. RF power output may be set in five-watt increments in the rangeof 20 to 100 watts, and ten-watt increments in the range of 100 to 200watts. Additionally, electrosurgical unit 10 may include an RF poweractivation display 64 comprising an indicator light that can illuminatewhen RF power is activated, either via a hand switch on electrosurgicaldevice 30 or a footswitch. Switches 62 a, 62 b comprise membraneswitches. While only one RF power selector 62 is shown, electrosurgicalunit 10 can have multiple such RF power selectors such as one each formonopolar and bipolar power selection.

The example electrosurgical unit 10 can also include fluid flow ratesetting display and flow rate setting selector. The display can includeindicator lights, and the flow rate selector can include switches.Pushing one of the flow rate switches selects a fluid flow rate, whichis than indicated in display.

Electrosurgical unit 10 can further include a fluid flow rate settingdisplay 66. Flow rate setting display 66 may comprise three indicatorlights 66 a, 66 b and 66 c with first light 66 a corresponding to afluid flow rate setting of low, second light 66 b corresponding to afluid flow rate setting of medium (intermediate) and third light 66 ccorresponding to a flow rate setting of high. One of these threeindicator lights will illuminate when a fluid flow rate setting isselected.

Electrosurgical unit 10 can further include a fluid flow selector 68comprising flow rate setting switches 68 a, 68 b and 68 c used to selector switch the flow rate setting. Three push switches may be providedwith first switch 68 a corresponding to the fluid flow rate setting oflow, second switch 68 b corresponding to a fluid flow rate setting ofmedium (intermediate) and third switch 68 c corresponding to a flow ratesetting of high. Pushing one of these three switches may select thecorresponding flow rate setting of low, medium (intermediate) or high.The medium, or intermediate, flow rate setting may be automaticallyselected as the default setting if no setting is manually selected.Switches 68 a, 68 b and 68 c may comprise membrane switches.

Before starting a surgical procedure, it may be desirable to primedevice 30 with fluid 12. Priming may be desirable to inhibit RF poweractivation without the presence of fluid 12. A priming switch 70 may beused to initiate priming of device 30 with fluid 12. Pushing switch 70once may initiate operation of pump 22 for a predetermined time periodto prime device 30. After the time period is complete, the pump 22 mayshut off automatically. When priming of device 30 is initiated, apriming display 72 comprising an indicator light may illuminate duringthe priming cycle.

While not being bound to a particular theory, the relationship betweenthe variables of fluid flow rate Q (such as in units of cubiccentimeters per minute (cc/min)) and RF power setting P_(S) (such as inunits of watts) can be configured to inhibit undesired effects such astissue desiccation, electrode sticking, smoke production, charformation, and other effects while not providing a fluid flow rate Q ata corresponding RF power setting P_(S) not so great as to disperse toomuch electricity and or overly cool the tissue at the electrode/tissueinterface. Electrosurgical unit 10 is configured to increase the fluidflow rate Q generally linearly with an increasing RF power setting P_(S)for each of the three fluid flow rate settings of low, medium, and high.

Electrosurgical unit 10 includes a set of receptacles 36 coupled tocircuitry and configured to receive cables. Receptacles 36 can includesbipolar power output receptacles 36 a, monopolar power outputreceptacles 36 b, and pad dispersive electrode receptacle 36 c. Thebipolar power output receptacles 36 a can include an electricalconnector configured to receive, for example, male banana plugconnectors attached to conductors operably coupled to a bipolarelectrosurgical device or bipolar elements of a multifunctionelectrosurgical device. In one example, the electrosurgical unit 10includes three bipolar power output receptacles 36 a. In one example,the bipolar power output receptacles 36 a include an active electrodereceptacle to be electrically coupled to an active electrode on theelectrosurgical device 30, a return electrode receptacle to beelectrically coupled to a return electrode on the electrosurgical device30, and a controller receptacle to provide control signals to the turnon and turn off the electrosurgical device. In some examples, thebipolar output receptacle can include one or more additional returnelectrical receptacles suitable for connecting to at least a secondreturn electrode for use with the electrosurgical device in the bipolarmode. The monopolar power out receptacles 36 b can be configured toreceive conductors operably coupled to a monopolar electrosurgicaldevice or monopolar elements of a multifunction electrosurgical device.The pad dispersive electrode receptacle 36 c can include a connector toreceive a conductor operably coupled to the pad dispersive electrode 32.In the example, the pad dispersive electrode receptacle 36 c and some orall of the bipolar output receptacles 36 a are coupled to detectioncircuits within the electrosurgical unit 10.

In some examples, the electrosurgical unit 10 can include a display or adata output couplable to an external monitor to provide graphical orindications of impedance of tissue between electrodes of theelectrosurgical device 30 and pad dispersive electrode 32 as determinedby the measurement circuits coupled to receptacles 36 a, 36 c.

FIG. 3 illustrates an example of an electrosurgical device 80, which cancorrespond with electrosurgical device 30, having at least a bipolarelectrode assembly 100 that that can be used in conjunction withelectrosurgical unit 10 and pad dispersive electrode 32. Bipolarelectrode assembly 100 includes distally extending electrodes 102, 104having exposed conductive surfaces configured to be electrically coupledto a source of bipolar RF energy supplied from electrosurgical unit 10as well as to measurement circuitry in electrosurgical unit 10.Electrode assembly 100 can be further configured as an active electrode102 and return electrode 104 for the purposes of illustration. In oneexample, electrodes 102, 104 are in a co-planar arrangement to providefor a robust electrode/tissue interface. Electrodes 102, 104 may beformed to optimize hemostatic sealing of bone and tissue or coagulationin conjunction with delivery of fluid or for a particular application oranatomical geometry.

Electrosurgical device 80 extending along longitudinal axis A includes ahandpiece 82. Handpiece 82 includes a handle 84 that can include afinger grip portion with ridges shown on the lower surface or bottom Bof the device 80 and intended to be held in the surgeon's hand. Thehandpiece 82 includes a proximal end 86 for balance and, in the example,includes an electrical connector for electrically coupling cable 24 tothe device 80.

Handpiece 82 may be configured to enable a user of electrosurgicaldevice 80 to hold and manipulate device 80 between the thumb and indexfinger like a writing instrument or an electrosurgical pen. Handpiece 82may comprise a sterilizable, rigid, electrically insulative material,such as a synthetic polymer (e.g., polycarbonate,acrylonitrile-butadiene-styrene). The handle 84 can include an uppersurface, or top T, opposite bottom B. A controller 88, such as a set ofone or more switches coupled to circuitry such as on a printed circuitboard, in the example is disposed on top T and configured to be operatedby the user's thumb or index finger to activate the electrode assembly100.

The electrosurgical device 80 can include a probe assembly 90 extendingdistally from the handpiece 82. The probe assembly 90 in the exampleincludes a shaft 94. The shaft 94, or other portions of electrosurgicaldevice 80 may include one or more elements forming a subassembly to begenerally one or more of rigid, bendable, fixed-length, variable-length(including telescoping or having an axially-extendable oraxially-retractable length) or other configuration.

In one example, the handle 84 and shaft 94 can be formed from aninsulative material such as a high temperature micromolded polymer.Examples insulative materials can include polytetrafluoroethylene(PTFE), polycarbonate (PC), polyoxymethylene (POM or acetal), orpolyether ether ketone (PEEK).

The shaft 94 carries one or more electrical conductors to a distal end96 including the electrode assembly 100. Electrical pathways within thehandpiece 80 and probe assembly 90 can be formed as conductive arms,wires, traces, other conductive elements, and other electrical pathwaysformed from electrically conductive material such as metal and maycomprise stainless steel, titanium, gold, silver, platinum or any othersuitable material. In the example, the shaft 94 includes a fluid lumenextending into the handpiece 82 for fluidly coupling to delivery tubing16 in cable 26. The fluid lumen includes an outlet port 106 disposed onthe electrode assembly 100 for selectively dispersing fluid 12. In oneexample, fluid lumen can be included in a hypotube configured to matewith delivery tubing 16 to supply fluid 12 to electrode assembly 100.Hypotube can be constructed from non-conductive commonly used flexibletubing, such as polyvinyl chloride (PVC), PEEK, or a thermoplasticelastomer (TPE). In one example, the TPE is a polyether block amide(PEBA) available under the trade designation PEBAX from Arkema ofColombes, France.

In one example, the controller 88 includes one or more pushbuttons 88 a,88 b on the handle 82 in combination with circuitry such as a printedcircuit board within the handle 82 to provide binary activation (on/off)control for each function of the electrosurgical device 80. For example,one button 88 a may be pressed to selectively activate the electrodeassembly 100 and disperse fluid from port 106 in a sealing function anddisperse fluid 12. Alternate configurations of the controller 88 and itsactivation are contemplated.

In some examples, the electrosurgical devices 30, 80 may be used inother systems or the electrosurgical unit 10 may be used with otherelectrosurgical devices. Other examples of electrosurgical device 30 caninclude bipolar electrodes mounted on jaws or clamps that are movablewith respect to each other. For example, jaws or clamps can selectivelypinch tissue between the bipolar electrodes. Still further examples caninclude any suitable configuration of active and return electrodes atthe treatment site. While the electrosurgical devices 30, 80 aredescribed with reference to electrosurgical unit 10 and other elementsof system 40, the description of the combination is for the purposes ofillustrating system 40.

FIG. 4 illustrates an environment 110 that exemplifies a method ofsystem 40 including an example electrosurgical device 80 with a remotesecond return electrode such as pad dispersive electrode 32 operablycoupled to electrosurgical unit 10. Environment 110 includes tissue 112subjected to bipolar treatment from electrosurgical device 80 havingactive electrode 102 and return electrode 104 in the presence of fluid12 at a tissue treatment site 114, such as a surgical site. Duringbipolar operation of the electrosurgical device 80, the electrosurgicalunit 10 provides an RF signal to the active electrode 102 at an activevoltage V_(a) and an active current i₁ to the active electrode 102 atthe treatment site 114. The electrosurgical unit 10 receives a returnvoltage V_(r) and a first return current i₂ from the return electrode104. A remote return electrode, such as a pad dispersive electrode 32 isoperably coupled to the tissue 112 at remote site 116 remote from thetreatment site 114 and provides a second return current i₃ toelectrosurgical unit 10. In the example, the remote electrode, or paddispersive electrode 32, is also at voltage V_(r). The example treatmentsite 114 is in the presence of a fluid 12 provided by theelectrosurgical device 80. In one example, the remote site 116 is not inthe presence of the fluid 12 provided by the electrosurgical device 80.Impedance of the tissue 112, or Z_(l) in the fluid 12 at the treatmentsite 114 can be determined as the voltage difference between the activeelectrode 102 and the return electrode 104 divided by the first returncurrent, or Z_(l)=(V_(a)−V_(r))/i₂. Impedance of the tissue 112, or Z₂between active electrode 102 and the remote electrode, or pad dispersiveelectrode 32, at the remote site 116 can be determined as the voltagedifference between the active electrode 102 and the remote electrodedivided by the second return current, or Z₂=(V_(a)−V_(r))/i₃. Theelectrosurgical unit 10 is configured to receive electrical signals fromenvironment 110 and calculate the change in impedances Z₁ and Z₂ todetermine when to adjust power to the active electrode 102.

FIG. 5 illustrates the system 40 including the electrosurgical unit 10coupled to an example electrosurgical device 80 configured for a bipolaroperation having an active electrode 102 and first return electrode 104and also to a second, or remote, return electrode 122, such as a paddispersive electrode 32. The electrosurgical unit 10 includes an activeconnection 124 that is configured to be electrically coupled to theactive electrode 102, a first return connection 126 that is configuredto be electrically coupled to the first return electrode 104, and asecond return connection 128 that is configured to be coupled to thesecond return electrode 122. In one example, the active electrodeconnection 124 and first return connection 126 can be included as partof the receptacles 36 such as the bipolar output receptacles 36 a. Inthis example, the second return connection 128 can be included as partof the receptacles 36 such as a second return electrode receptacle onthe bipolar output receptacles 36 a or the pad dispersive receptacle 36c. Other configurations are contemplated including the second returnconnection 128 having a receptacle that is separate from the paddispersive receptacle 36 c and the second return connection 128 beingincluded as part of the bipolar output receptacles 36 a.

The example electrosurgical unit 10 can include a controller 130, a highvoltage power supply 132, and an RF output circuit 134. The power supply132 provides high voltage power to the RF output circuit 134, whichconverts high voltage power, for example from a direct current, into RFenergy and delivers the RF energy to the active connection 124. The RFoutput circuit 134 is configured to generate a plurality of waveformshaving various duty cycles, peak voltages, crest factors, and othersuitable parameters. Further, the controller 130 can be configured tocause operation of the pump, such as pump 22, to deliver a fluid duringbipolar operation (not indicated)

The controller 130 in the example can include a processor 140 operablyconnected to a memory device 142. Examples of a memory device 142 caninclude a non-volatile memory device such as a read only memory (ROM),electronically programmable read only memory (EPROM), flash memory,non-volatile random access memory (NRAM) or other memory device, and avolatile memory device such as random access memory (RAM) or othermemory device. Memory device 142 can include various combinations of oneor both of non-volatile memory devices and volatile memory devices. Theprocessor 140 includes an output port that is operably connected to thepower supply 132, the RF output circuit 134, or both that allows theprocessor 140 to control the output of the electrosurgical unit 10according to a selected scheme. In some examples, the processor 140 mayinclude a microprocessor or a logic processor or other control circuit.

Any combination of hardware and programming may be used to implement thefunctionalities of the electrosurgical unit 10. Such combinations ofhardware and programming may be implemented in a number of differentways. For example, the programming for the electrosurgical unit 10 maybe processor executable instructions stored on at least onenon-transitory machine-readable storage medium, such as memory device142 and the hardware may include at least one processing resource, suchas processor 140, to execute those instructions. In some examples, thehardware may also include other electronic circuitry to at leastpartially implement at least one feature of electrosurgical unit 10. Insome examples, the at least one machine-readable storage medium, such asa memory device 142, may store instructions that, when executed by theprocessor 140, at least partially implement some or all features ofelectrosurgical unit 10 and. In such examples, electrosurgical unit 10may include the at least one machine-readable storage medium storing theinstructions and the at least one processing resource to execute amethod. The processor-executable instructions may be in the form of anapplication, such as a computer application or module of a computerapplication. In other examples, the functionalities of electrosurgicalunit 10 and method may be at least partially implemented in the form ofelectronic circuitry.

The electrosurgical unit 10 also includes a detection circuit 150electrically coupled to the first return connection 126, second returnconnection 128, and operably coupled to the controller 130. In oneexample, the detection circuit 150 can be operably coupled to the activeconnection 124 or receive signals indicative of the voltages or currentsprovided to the active electrode 102. The features and functionsdescribed below as included in the detection circuits such as detectioncircuit 150, in this disclosure may be, in some examples, included in orperformed with the controller 130, vice versa, or some othercombination. Furthermore, features and functionality of the detectioncircuit 150 can be implemented from one or more of conductors, circuitelements such as relays, hardware, and software. For example, thedetection circuit 150 can include circuit elements or paths operablycoupled to the RF circuit 134 or at least some of the bipolarreceptacles 36 a and the pad dispersive receptacles 36 c that areconfigured to provide a signal representative of the active and returnvoltages and return currents. The circuit elements can include currentprobes to measure currents of interest. The circuit elements can beprovided to an analog to digital converter that is then configured toprovide digital signals to the controller 130.

In the example, the detection circuit 150 is able to detect at least thereturn voltage or voltages, such as V_(r), at the first return electrode102 and the second return electrode 122, and can also be configured todetect the first and second return currents i₂ and i₃ provided from thefirst return electrode 104 and second return electrode 122. Thecontroller 130 also receives a signal indicating the active voltageV_(a) at the active electrode 102 and the active current i₁ providedfrom the active connection 124 to the active electrode 102. Thedetection circuit 150 and controller 130 operate together to determinethe impedances or impedances over time in the tissue forming anelectrical path between the active electrode 102 and the first returnelectrode 104 at the treatment site 114 and in the tissue forming theelectrical path between the active electrode 102 and the second returnelectrode 122 at the remote site 116 while treating tissue 112 duringsurgery. For example, controller 130 can receive a signal representativeof the voltages at the active electrode 102 and the return electrode 104and the first return current i₂, to calculate an impedance at thetreatment site 114 or Z₁=(V_(a)−V_(r))/i₂ and a signal representative ofthe voltages at the active electrode 102 and the remote electrode 122and the second return current i₃, to calculate an impedance at theremote site 116, or Z₂=(V_(a)−V_(r))/i₃.

The illustrated examples contemplate that the voltage value at the firstreturn electrode is set to the voltage value at the second returnelectrode, or V_(r). In other examples, the detection circuit 150 mayprovide independent voltage values for the voltages at the first returnelectrode and the second return electrode that may or may not be equalto each other. In still other examples, the electrosurgical unit mayreceive more than two return currents or return voltages from ore thantwo return electrodes and determine two or more impedance measurementsat sites remote from the treatment site 112. Still other examples arecontemplated.

In one example, controller 130 can include features to present theimpedance measurement over time as a visualization to a display orscreen as a graph, chart, numerical value, or other visual indication.In another example, the controller 130 can include an indicator deviceto provide an audio indication or visual indication, such as an alarmsound or lights, upon a selected condition of the impedance measurementsor the impedance measurement at the remote site 116. The impedancemeasurement indicative of a selected condition, in one example, can berelated impedance of the tissue at the remote site 116 if the impedanceof the tissue at the treatment site 114 is noisy or determined to be ofsecondary importance to the impedance of the tissue at the treatmentsite 114. Other selected conditions of interest may be detected via theimpedance measurements. A clinician can receive an indication that animpedance threshold representative of the selected condition has beenreached, and selectively adjust the RF energy to the active electrode84, i.e., such as reduce or cut power, or take other action accordingly.Still further, the controller 130 can include a component toautomatically adjust power or signals to the active electrode 102 of theelectrosurgical device upon detection of a selected condition via theimpedance measurement.

FIG. 6 illustrates an example method 160 for use with theelectrosurgical system 40 including the electrosurgical unit 10.Electrosurgical treatment with an RF energy is provided to tissue 112via an active electrode, such as active electrode 102 at a treatmentsite, such as treatment site 114, and a first return electrode, such asfirst return electrode 104, at the treatment site at 162. In thisexample, the active electrode and first return electrode are configuredfor bipolar operation. An electrical circuit of RF energy is createdbetween the active electrode and the first return electrode at thetreatment site 114. Further, the RF energy can be provided in thepresence of a fluid, such as fluid 12, at the treatment site 114. Duringthe electrosurgical treatment an impedance measurement is determined inthe tissue 112 between the active electrode at the treatment site and asecond return electrode, such as second return electrode 122 or paddispersive electrode 32, disposed remote from the treatment site such asat remote site 116 at 174. As indicated in the example electrosurgicalunit 10, the controller 130 can receive signals representative ofvoltages and currents from detection circuit 150 and determine theimpedance in the tissue 112 at the remote site 116 viaZ₂=(V_(a)−V_(r))/i₃. The electrosurgical treatment can be based on thisimpedance, such as selected parameters of this impedance includingimpedance over time, at 176. In one example, the controller 130 cancause the RF output circuit 134 to stop providing RF energy to theelectrosurgical device 30 if the impedance has plateaued or otherdetected and selected feature of the impedance.

As described, impedance of tissue at the treatment site 114 willincrease with thermal delivery as a function of time until the impedancereaches a plateau, at which point thermal delivery will no longer treatthe tissue as intended, or ineffectively treat the tissue. When theimpedance reaches the plateau, the impedance measurement as a functionof time exhibits a characteristic that generally indicates furthersubjecting the tissue to RF energy at the power level will no longerprovide effective treatment. In one example, a characteristic of animpedance plateau can include a general leveling off of the rate ofchange of impedance as a function of time, whereas during effectivetreatment the rate of change of impedance as a function of time mayincrease. In one illustrated example, the impedance plateau can bereached at approximately one second of thermal treatment. In somecircumstances of bipolar treatment, however, the impedance plateau isdifficult to detect with a bipolar electrosurgical device such as device30 and historical electrosurgical units. For example, the presence of aconductive fluid 12 such as saline in the area of thermal deliveryduring hemostasis may add a parallel electrical load to the tissue 112between the active electrode and the return electrode of the bipolarelectrosurgical device. The parallel load in the presence of tissue canaffect the impedance measurement in the form of electrical noise thatcan adversely affect the ability of the historical electrosurgical unitto determine whether to adjust power. In the illustrated example, anelectrosurgical device that detects impedance in the tissue between theactive and return electrodes on the electrosurgical device may notdetect the impedance plateau until approximately 2.6 seconds, which isover twice as long after effective treatment has completed.

In the present example, using system 40 with electrosurgical unit 10 toprovide a bipolar treatment with the presence of a conductive fluid 12,the impedance plateau may be detected significantly sooner. In theelectrosurgical unit 10, the controller 130 can cause the RF outputcircuit 134 to adjust power to the electrosurgical device 30 upondetection of the impedance plateau as measured in the tissue between theactive electrode 102 and the second return electrode 122 and provide fora more effective treatment.

FIG. 7 illustrates an example method 170 for use with theelectrosurgical system 40 including the electrosurgical unit 10.Electrosurgical treatment is provided to tissue 112 via an activeelectrode, such as active electrode 102 at a treatment site, such astreatment site 114, and a first return electrode, such as first returnelectrode 104, at the treatment site at 172. In this example, the activeelectrode and first return electrode are configured for bipolaroperation. An electrical circuit of RF energy is created between theactive electrode and the first return electrode at the treatment site114. Further, the RF energy can be provided in the presence of a fluid,such as fluid 12, at the treatment site 114. During the electrosurgicaltreatment both a first impedance measurement is determined in the tissuebetween the active electrode at the treatment site and first returnelectrode at the treatment site and a second impedance measurement isdetermined in the tissue 112 between the active electrode at thetreatment site and a second return electrode, such as second returnelectrode 122 or pad dispersive electrode 32, disposed remote from thetreatment site such as at remote site 116 at 174. As indicated in theexample electrosurgical unit 10, the controller 130 can receive signalsrepresentative of voltages and currents from detection circuit 150 anddetermine the first impedance in the tissue 112 at the treatment site114 via Z₁=(V_(a)−V_(r))/i₂ and the second impedance at the remote site116 via Z₂=(V_(a)−V_(r))/i₃.

The electrosurgical treatment can be based on a comparison of the firstimpedance to the second impedance, such as selected parameters of firstand second impedance including impedance over time, at 176. For example,the treatment can be adjusted based on the comparison of the first andsecond impedance measurements. In one example, the controller 130 cancause the RF output circuit 134 to stop providing RF energy to theelectrosurgical device 30 if the one or the other of the impedancemeasurements has plateaued or other detected and selected feature of thecomparison of impedance at 176. In one example, a look up table ofimpedance characteristics can be stored in a memory device, such asmemory device 142 and compared to the measured or detected impedances at176. Power may be adjusted or cut off to the electrosurgical device 30via controller 130 and RF output circuit 134 if, for example, the secondimpedance measurement over time has started to plateau and the firstimpedance measurement is noisy. In some examples, power may be adjustedor cutoff if the first impedance measurement over time has started toplateau but the second impedance measurement has not started to plateau.Other outputs from the controller 130 and electrosurgical device 10 maybe provided based on various combinations of the characteristics of thefirst and second impedance measurements as determined in the comparisonat 176.

The example methods 600, 700 can be implemented to include a combinationof one or more hardware devices and computer programs for controlling asystem, such as a electrosurgical unit 10 having a processor 140 andmemory 142, to perform methods 600, 700 apply electrosurgical treatmentto tissue 112 at a treatment site 114 and detect impedance in tissue 112with a return electrode at a remote site 116. Methods 600, 700 can beimplemented as a computer readable medium or computer readable devicehaving set of executable instructions for controlling the processor toperform the method 100. In one example, computer storage medium, ornon-transitory computer readable medium, includes RAM, ROM, EEPROM,flash memory or other memory technology, that can be used to store thedesired information and that can be accessed by the computing system.Accordingly, a propagating signal by itself does not qualify as storagemedia. Computer readable medium may be located with the electrosurgicalsystem 40, the electrosurgical unit 10 or on a computing device onnetwork communicatively connected to the electrosurgical unit 10.Methods 600, 700 can be applied as computer program, or computerapplication implemented as a set of instructions stored in the memory,and the processor can be configured to execute the instructions toperform a specified task or series of tasks. In one example, thecomputer program can make use of functions either coded into the programitself or as part of library also stored in the memory.

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method for use with an active electrode and a plurality of return electrodes, the method comprising: providing an electrosurgical treatment with a treatment signal to tissue via the active electrode at a treatment site and a first return electrode of the plurality of return electrodes, wherein the active electrode and the first return electrode are in bipolar operation at the treatment site; and determining an impedance measurement of an impedance in the tissue between the active electrode at the treatment site and a second return electrode of the plurality of return electrodes, the second return electrode being at a site remote from the treatment site to receive the treatment signal, the impedance measurement determined from the treatment signal received at the second return electrode.
 2. The method of claim 1 comprising adjusting the electrosurgical treatment via the active electrode based on the impedance measurement.
 3. The method of claim 2 wherein the adjusting the electrosurgical treatment includes cutting power to the active electrode in response to a plateau in the impedance measurement.
 4. The method of claim 3 wherein the plateau includes a leveling off of the rate of change of impedance as a function of time.
 5. The method of claim 1 wherein providing the electrosurgical treatment includes providing a radio-frequency (RF) energy to the tissue.
 6. The method of claim 5 wherein the providing the electrosurgical treatment includes operating the electrosurgical device in a bipolar mode.
 7. The method of claim 5 wherein providing the electrosurgical treatment includes providing a fluid at the treatment site and not the remote site.
 8. The method of claim 7 wherein providing the fluid includes providing a conductive fluid.
 9. The method of claim 1 wherein the electrosurgical treatment includes a hemostatic sealing of the tissue.
 10. The method of claim 1 wherein the electrosurgical device includes a bipolar sealer.
 11. A method for use with an active electrode and a plurality of return electrodes, the method comprising: providing an electrosurgical treatment with a treatment signal to tissue via the active electrode at a treatment site and a first return electrode of the plurality of return electrodes, wherein the active electrode and the first return electrode are in bipolar operation at the treatment site; determining a first impedance measurement of an impedance in the tissue between the active electrode at the treatment site and the first return electrode at the treatment site, the first impedance measurement determined from the treatment signal received at the first return electrode; determining a second impedance measurement of an impedance in the tissue between the active electrode at the treatment site and a second return electrode of the plurality of return electrodes, the second return electrode being at a site remote from the treatment site to receive the treatment signal, the second impedance measurement determined from the treatment signal received at the second return electrode; and adjusting the treatment based on a comparison of the first impedance measurement with the second impedance measurement.
 12. The method of claim 11 wherein the comparison includes detecting an impedance plateau in the second impedance measurement.
 13. The method of claim 12 wherein the comparison includes detecting an impedance plateau in the second measurement and not in the first impedance measurement.
 14. The method of claim 13 wherein the first impedance measurement is noisy.
 15. The method of claim 13 wherein the adjusting treatment includes cutting power to the electrosurgical device.
 16. The method of claim 11 wherein the first return electrode and second return electrode are at a same potential.
 17. The method of claim 16 wherein the second impedance measurement include a difference in potential between the active electrode and the second return electrode divided by a current in the second return electrode during the treatment.
 18. The method of claim 17 wherein the second impedance measurement is an impedance as a function of time.
 19. The method of claim 11 wherein the plurality of return electrodes are two return electrodes.
 20. The method of claim 11 wherein the active electrode and the first remote electrode are included on a bipolar device configured to provide a fluid at the treatment site.
 21. A non-transitory computer readable medium to store computer executable instructions to control a processor to: provide an electrosurgical treatment with a treatment signal to tissue via an active electrode at a treatment site and a first return electrode of a plurality of return electrodes, wherein the active electrode and the first return electrode are in bipolar operation at the treatment site; and determine an impedance measurement of an impedance in the tissue between the active electrode at the treatment site and a second return electrode of the plurality of return electrodes, the second return electrode being at a site remote from the treatment site to receive the treatment signal, the impedance measurement determined from the treatment signal received at the second return electrode.
 22. The non-transitory computer readable medium of claim 21 wherein the impedance measurement includes a difference between electrical potentials measured in the active electrode and the second return electrode divided by a current received from the second return electrode.
 23. The non-transitory computer readable medium of claim 22 wherein the electrical potential of the second return electrode is set as the same as an electrical potential of the first return electrode.
 24. The non-transitory computer readable medium of claim 21 comprising providing a visualization of the impedance measurement.
 25. A non-transitory computer readable medium to store computer executable instructions to control a processor to: provide an electrosurgical treatment with a treatment signal to tissue via an active electrode at a treatment site and a first return electrode of a plurality of return electrodes, wherein the active electrode and the first return electrode are in bipolar operation at the treatment site; determine a first impedance measurement of an impedance in the tissue between the active electrode at the treatment site and the first return electrode at the treatment site, the first impedance measurement determined from the treatment signal received at the first return electrode; determine a second impedance measurement of an impedance in the tissue between the active electrode at the treatment site and a second return electrode of the plurality of return electrodes, the second return electrode being at a site remote from the treatment site to receive the treatment signal, the second impedance measurement determined from the treatment signal received at the second return electrode; and adjust the treatment based on a comparison of the first impedance measurement with the second impedance measurement.
 26. The non-transitory computer readable medium of claim 25 wherein the second impedance measurement includes a difference between electrical potentials measured in the active electrode and the second return electrode divided by a current received from the second return electrode.
 27. The non-transitory computer readable medium of claim 26 wherein the first impedance measurement includes a difference between electrical potentials measured in the active electrode and the first return electrode divided by a current received from the first return electrode.
 28. The non-transitory computer readable medium of claim 26 wherein the electrical potential of the second return electrode is set as the same as an electrical potential of the first return electrode.
 29. The non-transitory computer readable medium of claim 25 comprising selectively cutting power to the active electrode upon a detection of a plateau in the second impedance measurement.
 30. The non-transitory computer readable medium of claim 29 comprising selectively cutting power to the active electrode if a plateau in the first impedance measurement is not detected.
 31. The non-transitory computer readable medium of claim 25 comprising providing an alert upon a detection of a plateau in the second impedance measurement.
 32. The non-transitory computer readable medium of claim 31 comprising providing a visualization of the second impedance measurement.
 33. The non-transitory computer readable medium of claim 32 wherein the visualization includes a graph on a display.
 34. An electrosurgical unit for use with an active electrode and a plurality of return electrodes, the electrosurgical unit comprising: a memory to store a set of instructions; and a processor to execute the set of instructions to: provide an electrosurgical treatment with a treatment signal to tissue via the active electrode at a treatment site and a first return electrode of the plurality of return electrodes, wherein the active electrode and the first return electrode are in bipolar operation at the treatment site; and determine an impedance measurement of an impedance in the tissue between the active electrode at the treatment site and a second return electrode of the plurality of return electrodes, the second return electrode being at a site remote from the treatment site to receive the treatment signal, the impedance measurement determined from the treatment signal received at the second return electrode.
 35. The electrosurgical unit of claim 34 wherein the impedance measurement includes a difference between electrical potentials measured in the active electrode and the second return electrode divided by a current received from the second return electrode determined with the processor.
 36. The electrosurgical unit of claim 35 wherein the electrical potential of the second return electrode is set as the same as an electrical potential of the first return electrode with a detection circuit operably coupled to the processor.
 37. The electrosurgical unit of claim 34 comprising providing a visualization of the impedance measurement on a display operably coupled to the processor.
 38. An electrosurgical unit for use with an active electrode and a plurality of return electrodes, the electrosurgical unit comprising: a memory to store a set of instructions; and a processor to execute the set of instructions to: provide an electrosurgical treatment with a treatment signal to tissue via the active electrode at a treatment site and a first return electrode of the plurality of return electrodes, wherein the active electrode and the first return electrode are in bipolar operation at the treatment site; determine a first impedance measurement of an impedance in the tissue between the active electrode at the treatment site and the first return electrode at the treatment site, the first impedance measurement determined from the treatment signal received at the first return electrode; determine a second impedance measurement of an impedance in the tissue between the active electrode at the treatment site and a second return electrode of the plurality of return electrodes, the second return electrode being a site remote from the treatment site to receive the treatment signal, the second impedance measurement determined from the treatment signal received at the second return electrode; and adjust the treatment based on a comparison of the first impedance measurement with the second impedance measurement.
 39. The electrosurgical unit of claim 38 wherein the second impedance measurement includes a difference between electrical potentials measured in the active electrode in a detection circuit and the second return electrode divided by a current received from the second return electrode at the detection circuit, the detection circuit operably coupled to the processor.
 40. The electrosurgical unit of claim 39 wherein the first impedance measurement includes a difference between electrical potentials measured in the active electrode and the first return electrode in the detection circuit divided by a current received from the first return electrode at the detection circuit.
 41. The electrosurgical unit of claim 39 wherein the electrical potential of the second return electrode is set as the same as an electrical potential of the first return electrode at a detection circuit at the detection circuit.
 42. The electrosurgical unit of claim 38 comprising selectively cutting power to the active electrode upon a detection of a plateau in the second impedance measurement via a signal from the processor to an RF circuit.
 43. The electrosurgical unit of claim 42 comprising selectively cutting power to the active electrode if a plateau in the first impedance measurement is not detected.
 44. The electrosurgical unit of claim 38 comprising providing an alert upon a detection of a plateau in the second impedance measurement in response to a signal from the processor.
 45. The electrosurgical unit of claim 44 comprising providing a visualization of the second impedance measurement in response to another signal from the processor.
 46. The electrosurgical unit of claim 45 wherein the visualization includes a graph on a display operably coupled to the processor.
 47. An electrosurgical unit configured to provide a treatment with a bipolar electrosurgical device at a treatment site, the bipolar electrosurgical device having an active electrode and a first return electrode at the treatment site, and a second return electrode at a remote site, comprising: an RF circuit operably coupled to an output having an active electrode connection and a first return connection, the active electrode connection and the first return connection configured to be coupled to the bipolar electrosurgical device, the RF circuit configured to provide a bipolar operation of the bipolar electrosurgical device via the active electrode connection and the first return connection with a treatment signal; detection circuit configured to be operably coupled to the active electrode connection and the first return electrode connection, the detection circuit further configure to be operably coupled to a second return electrode connection, the second return electrode connection configured to be coupled to a second return electrode at a remote site; and a processor operably coupled to the detection circuit and configured to detect a potential difference from the treatment signal between the active electrode connection and the second return electrode connection and a current from on the treatment signal in the second return electrode connection, and to determine an impedance measurement based on the potential difference and the current during bipolar operation.
 48. The electrosurgical unit of claim 47 wherein the processor is operably coupled to a display to provide a visualization of impedance in tissue over a period of time.
 49. The electrosurgical unit of claim 47 comprising a fluid pump to selectively provide a conductive fluid during the bipolar operation.
 50. An electrosurgical unit configured to provide a treatment with a bipolar electrosurgical device at a treatment site, the bipolar electrosurgical device having an active electrode and a first return electrode at the treatment site, and a second return electrode at a remote site, the electrosurgical unit comprising: a controller operably coupled to an RF circuit and configured to provide bipolar operation of the active electrode and the first return electrode with a treatment signal via the RF circuit; a detection circuit operably coupled to the controller, the detection circuit configured to receive an electrical potential from the second return electrode and current from the second return electrode; wherein the controller determines an impedance measurement of an impedance between the active electrode and the second return electrode during the treatment, the impedance measurement determined from the electrical potential from the second return electrode and the a current from the second return electrode from the treatment signal. 